Difference between revisions of "VPN over SSH"

From ArchWiki
Jump to: navigation, search
m (Helper script: Use AUR template.)
(Create tun interfaces using systemd-networkd)
 
(11 intermediate revisions by 6 users not shown)
Line 1: Line 1:
 
[[Category: Virtual Private Network]]
 
[[Category: Virtual Private Network]]
 +
[[Category:Secure Shell]]
 
There are several ways to set up a Virtual Private Network through SSH. Note that, while this may be useful from time to time, it may not be a full replacement for a regular VPN. See for example [http://sites.inka.de/bigred/devel/tcp-tcp.html].
 
There are several ways to set up a Virtual Private Network through SSH. Note that, while this may be useful from time to time, it may not be a full replacement for a regular VPN. See for example [http://sites.inka.de/bigred/devel/tcp-tcp.html].
  
Line 6: Line 7:
 
OpenSSH has built-in TUN/TAP support using -w<local-tun-number>:<remote-tun-number>. Here, a layer 3/point-to-point/ TUN tunnel is described. It is also possible to create a layer 2/ethernet/TAP tunnel.
 
OpenSSH has built-in TUN/TAP support using -w<local-tun-number>:<remote-tun-number>. Here, a layer 3/point-to-point/ TUN tunnel is described. It is also possible to create a layer 2/ethernet/TAP tunnel.
  
=== Create tun interfaces ===
+
=== Create tun interfaces using netctl ===
  
 
Create tun interfaces:
 
Create tun interfaces:
Line 21: Line 22:
 
SKIPNOCARRIER='yes'
 
SKIPNOCARRIER='yes'
 
ADDR='<IP>'
 
ADDR='<IP>'
IPCFG=('route add <REMOTE-NETWORK/MASK> via <REMOTE-SIDE-IP>')
+
IPCFG=('ip route add <REMOTE-NETWORK/MASK> via <REMOTE-SIDE-IP>')
 
}}
 
}}
  
 
Then do 'netcfg -u vpn' or add it into /etc/conf.d/netcfg.
 
Then do 'netcfg -u vpn' or add it into /etc/conf.d/netcfg.
  
Also You may manage tun interfaces with 'ip tunnel' command.
+
=== Create tun interfaces using systemd-networkd ===
 +
 
 +
{{bc|1=
 +
$ cat /etc/systemd/network/vpn.netdev
 +
[NetDev]
 +
Name=tun5
 +
Kind=tun
 +
MTUBytes=1480
 +
 
 +
[TUN]
 +
User=vpn
 +
Group=network
 +
 
 +
$ cat /etc/systemd/network/vpn.network
 +
[Match]
 +
Name=tun5
 +
 
 +
[Address]
 +
Address=192.168.200.2/24
 +
}}
 +
 
 +
Once these files are created, enable them by restarting systemd-networkd
 +
 
 +
{{bc|1=
 +
# systemctl restart systemd-networkd.service
 +
}}
 +
 
 +
Also you may manage tun interfaces with 'ip tunnel' command.
  
 
==== Creating interfaces in SSH command ====
 
==== Creating interfaces in SSH command ====
  
SSH can create both interfaces automatically, but you should configure IP and routing after connection established.
+
SSH can create both interfaces automatically, but you should configure IP and routing after the connection is established.
  
 
{{bc|1=
 
{{bc|1=
Line 60: Line 88:
  
 
* ssh should have access rights to tun interface or permissions to create it. Check owner of tun interface and/or /dev/net/tun.
 
* ssh should have access rights to tun interface or permissions to create it. Check owner of tun interface and/or /dev/net/tun.
* Obviously if you want to access network (not single machine) you should set up properly IP packet forwarding, routing and maybe netfilter on both sides.
+
* Obviously if you want to access a network rather than a single machine you should properly set up IP packet forwarding, routing and maybe a netfilter on both sides.
  
 
== Using PPP over SSH ==
 
== Using PPP over SSH ==
  
[[Pppd|pppd]] can easily be used to create a tunnel through an SSH server:
+
[[pppd]] can easily be used to create a tunnel through an SSH server:
  
 
{{ic|/usr/sbin/pppd updetach noauth silent nodeflate pty "/usr/bin/ssh root@remote-gw /usr/sbin/pppd nodetach notty noauth" ipparam vpn 10.0.8.1:10.0.8.2}}
 
{{ic|/usr/sbin/pppd updetach noauth silent nodeflate pty "/usr/bin/ssh root@remote-gw /usr/sbin/pppd nodetach notty noauth" ipparam vpn 10.0.8.1:10.0.8.2}}
Line 81: Line 109:
  
 
=== Helper script ===
 
=== Helper script ===
[https://github.com/halhen/pvpn pvpn] (available in [[AUR]] package {{aur|pvpn}}) is a wrapper script around {{ic|pppd}} over SSH.
+
[https://github.com/halhen/pvpn pvpn] (available in [[AUR]] package {{AUR|pvpn}}) is a wrapper script around {{ic|pppd}} over SSH.
  
 
== See also ==
 
== See also ==

Latest revision as of 16:37, 7 June 2016

There are several ways to set up a Virtual Private Network through SSH. Note that, while this may be useful from time to time, it may not be a full replacement for a regular VPN. See for example [1].

OpenSSH's built in tunneling

OpenSSH has built-in TUN/TAP support using -w<local-tun-number>:<remote-tun-number>. Here, a layer 3/point-to-point/ TUN tunnel is described. It is also possible to create a layer 2/ethernet/TAP tunnel.

Create tun interfaces using netctl

Create tun interfaces:

$ cat /etc/network.d/vpn
INTERFACE='tun5'
CONNECTION='tuntap'
MODE='tun'
USER='vpn'
GROUP='network'

IP='static'
SKIPNOCARRIER='yes'
ADDR='<IP>'
IPCFG=('ip route add <REMOTE-NETWORK/MASK> via <REMOTE-SIDE-IP>')

Then do 'netcfg -u vpn' or add it into /etc/conf.d/netcfg.

Create tun interfaces using systemd-networkd

$ cat /etc/systemd/network/vpn.netdev 
[NetDev]
Name=tun5
Kind=tun
MTUBytes=1480

[TUN]
User=vpn
Group=network

$ cat /etc/systemd/network/vpn.network 
[Match]
Name=tun5

[Address]
Address=192.168.200.2/24

Once these files are created, enable them by restarting systemd-networkd

# systemctl restart systemd-networkd.service

Also you may manage tun interfaces with 'ip tunnel' command.

Creating interfaces in SSH command

SSH can create both interfaces automatically, but you should configure IP and routing after the connection is established.

ssh \
  -o PermitLocalCommand=yes \
  -o LocalCommand="sudo ifconfig tun5 192.168.244.2 pointopoint 192.168.244.1 netmask 255.255.255.0" \
  -o ServerAliveInterval=60 \
  -w 5:5 vpn@example.com \
  'sudo ifconfig tun5 192.168.244.1 pointopoint 192.168.244.2 netmask 255.255.255.0; echo tun0 ready'

Start SSH

ssh -f -w5:5 vpn@example.com -i ~/.ssh/key "sleep 1000000000"

or you may add keep-alive options if you are behind a NAT.

ssh -f -w5:5 vpn@example.com \
        -o ServerAliveInterval=30 \
        -o ServerAliveCountMax=5 \
        -o TCPKeepAlive=yes \
        -i ~/.ssh/key "sleep 1000000000"

Troubleshooting

  • ssh should have access rights to tun interface or permissions to create it. Check owner of tun interface and/or /dev/net/tun.
  • Obviously if you want to access a network rather than a single machine you should properly set up IP packet forwarding, routing and maybe a netfilter on both sides.

Using PPP over SSH

pppd can easily be used to create a tunnel through an SSH server:

/usr/sbin/pppd updetach noauth silent nodeflate pty "/usr/bin/ssh root@remote-gw /usr/sbin/pppd nodetach notty noauth" ipparam vpn 10.0.8.1:10.0.8.2

When the VPN is established, you can route traffic through it. To get access to an internal network:

ip route add 192.168.0.0/16 via 10.0.8.2

To route all Internet traffic through the tunnel, for example to protect your communication on an unencrypted network, first add a route to the SSH server through your regular gateway:

ip route add <remote-gw> via <current default gateway>

Next, replace the default route with the tunnel

ip route replace default via 10.0.8.2

Helper script

pvpn (available in AUR package pvpnAUR) is a wrapper script around pppd over SSH.

See also